1. Field of Invention
The present invention relates to data security between server computers and client computers in data networks, and more particularly relates to systems for managing, in a proxy server computer, digital certificates for two-way interactive communication devices over the data networks; wherein the two-way interactive communication devices, such as mobile devices, cellular phones, landline telephones and Internet appliance controllers, have generally limited computing resources such as computing power, memory and graphical display capability.
2. Description of the Related Art
A fast-growing trend on the Internet is electronic commerce. The electronic commerce is an integrative concept designed to draw together a wide range of business support services, trading support systems for commodities, products, customized products and custom-built goods and services; ordering and logistic support systems; settlement support systems; and management information and statistical reporting systems, all via the Internet. It is well known, however, that the Internet is a wide open, public and international network of interconnected computers and electronic devices around the world. The ability to send and receive secure data becomes a fundamental requirement in conducting electronic commerce over the Internet. To transact business over the open network, a business or organization must have an efficient and reliable manner to establish its identity and credibility to protect itself and its customers from imposters. Similarly, customers need assurance that their private information they may submit over the Internet can not be read by anyone but the business that they submit to.
One of the on-going efforts to ensure private communications or business transactions between two authenticated parties is to use digital certificates to bind the identities of the two parties to a pair of electronic keys that can be used to encrypt and sign digital information transmitted over the Internet. A digital certificate makes it possible to verify someone's claim that they have the right to use a given key, which helps prevent others from using phony keys to impersonate authorized users. Used in conjunction with encryption, digital certificates provide a more complete security solution by assuring the identity of all parties involved in a transaction through an open network.
The current architecture for using the digital certificates is binding between two computers, one being a client computer and the other being a server computer, on the Internet, that means both computers physically hold their own certificates, requiring a memory space to keep certificates. In case, one of the certificates becomes invalid (expired, revoked or no longer usable), the computer that owns the invalid certificate may acquire a new certificate from a certificate issuing authority. However, the acquiring process generally takes a number of minutes and a significant amount of computing power. When a communication session between the two computers is established, the two computers authenticate each other by examining the counterpart's certificate. A session key is created when the authentication is successful and a secure communication session thus commences using the session key to encrypt all information exchanging between the two computers. The authentication process also takes a significant amount of computing power.
When the client computer is a small two-way communication device such as a mobile computing device, a cellular phone, a landline telephone, or an Internet appliance controller, the above architecture is hardly applicable. To increase the portability and mobility, most of such two-way communication devices are designed small in size, light in weight, low in power consumption and as economically as possible. Such designs, often considered as thin-client designs, result in a very limited computing power, typically equivalent to less than one percent of what is provided in a typical desktop or portable computer and the memory capacity thereof is generally less than 250 kilobytes. That means that the thin client devices would not have extra memory spaces to store a number of certificates and the required computing power to acquire a new certificate in real time if one of the possessed certificates becomes invalid. There is thus a great need for providing the thin clients with a mechanism to effectively manage the certificates.